Sonophotocatalytic Degradation Research Articles

Photocatalytic and sonophotocatalytic degradation of rhodamine B by nano-sized La2Ti2O7 oxides synthesized with sol-gel method

Nano-sized La2Ti2O7 oxides were synthesized by sol-gel route. The photocatalytic properties of the Rhodamine B degradation on this photocatalyst were studied as a function of crystallite size, dye concentration, catalyst loading, temperature and intensity of UV light flux. The photocatalytic results as well as the microstructural analysis, carried out by X-ray Diffraction and Transmission Electron Microscopy, revealed a strong correlation between the apparent rate constant and the crystallite size/degree of crystallinity of the photocatalyst. Temperature studies have shown optimum photocatalysis at 40 °C. Measurements of the zeta potential as a function of pH made it possible to determine the point of zero charge of the photocatalyst at pH = 8 and to understand the influence of pH on the degradation of cationic or anionic pollutants. Finally, the sonophotocatalytic process was studied showing a noticeable improvement in the apparent rate constant, multiplied by a factor of ∼1.7 compared to photocatalysis alone. The synergistic effect was quantified via measurements in sonocatalysis alone and then coupled to UV irradiation. This synergistic effect is about 23 % in the case of degradation of Rhodamine B on La2Ti2O7 oxides synthesized at 1000 °C.

Performance and reaction mechanism of MgO/ZnO/Graphene ternary nanocomposite in coupling with LED and ultrasound waves for the degradation of sulfamethoxazole and pharmaceutical wastewater

In this paper, we investigated sonophotocatalytic degradation of sulfamethoxazole (SUX) antibiotic in pharmaceutical wastewaters by employing a ternary heterostructure catalyst composed of MgOand ZnO nanoparticles anchored on graphene nanosheets (MZG) under UV-A (LED) and US irradiations as a novel study. Synthesis of MZG was performed via multi-step hydrothermal-assisted method and characterizedby employing XRD, FT-IR, FESEM, BET, EIS, DRS, EDS, TEM, EDX, and TGA techniques. By introduction of ZnO and graphene, photocatalytic activity of MgO was enhanced in both UV and visible regions. A good catalytic potential and significant synergistic effect was obtained for ternary system (MZG/LED/US) compared to binary and single processes. After 120 min of sonophotocatalytic treatment, complete degradation of SUX (55 mg/L) can be attained at MZG: 0.8 g/L, pH: 9.0, LED power: 90 W and US power: 250 W. Kinetic studies revealed that sonophotocatalytic degradation process followed the pseudo first-order kinetic model. HO species were detected as dominant oxidative free radicals which contributed in SUX degradation process. A comprehensive possible mechanism was proposed for photocatalysis and sonocatalysis processes involved in MZG/LED/US system in detail. The nanocomposite was reused for six successive cycles with maximum 9.8% drop in degradation efficiency. An efficient improvement was achieved in the biodegradability of real pharmaceutical wastewater after treatment by MZG/LED/US with 94% and 81% removal of COD and TOC, respectively. To conclude, combining MZG, LED and US waves can be utilized as a novel and efficient strategy to treat real pharmaceutical wastewaters in practical applications, owing to high performance in degradation/mineralization, excellent reusability potential and high activity in sonolysis and photolysis systems.

Hybrid Sono-photocatalytic degradation of Acid Brown 14 Using Persulphate and ZnO Nanoparticles: Feasibility and kinetic Study

ABSTRACT Degradation of acid brown 14 (AB14) was studied using ultrasound/ultraviolet for heterogeneous activation of persulphate and ZnO nanoparticle. Various operating parameters including AB14 initial concentration, pH, ZnO dose, anion concentration, ultrasound, as well as ultraviolet synergic effect and scavenging factors were evaluated. The maximum dye removal was observed at a high persulphate concentration, acidic pH, low initial day concentration, and under the simultaneous ultrasound/ultraviolet irradiations plus presence of ZnO. AB14 removal efficiency was elevated from 15% to 75% when ZnO was added as a catalyst. The kinetic study revealed that the experimental data had the best fit with the second-order kinetic model (R2: 0.92) with the rate constant of 0.0025 min−1. The scavenging test indicated that the sulphate radicals were the dominant species during the AB14 degradation. Finally, the high removal efficiency of AB14 (nearly to 100%) suggests that this process is efficient for removal of organic dyes from aqueous solutions.

Sonolytic, sonocatalytic and sonophotocatalytic degradation of carboxymethyl cellulose (CMC): kinetic and mechanisms

In this research, enzymatic degradation of carboxymethyl cellulose (CMC) with different concentration of substrate was studied using stable available parameters of Michaelis-Menton and calculated maximum reaction rate Vmax. We also used effective approaches such as ultrasonic, sonocatalytic and sonophotocatalytic irradiation in the presence of TiO2 nanoparticles as pretreatment. Degradation of the cellulose by means of ultrasound irradiation and its combination with heterogeneous (TiO2) was investigated. The emphasis was on evaluating theeffect of additives on degradation rate constants. Ultrasound irradiation (24 kHz) was provided by a sonicator, while an ultraviolet source of 16 W was used for UV irradiation. The extent of sonolytic degradation increased when ultrasound power (in the range 1560 W) increased, and the presence of TiO2 did not have significant effect on degradation. We should also note that TiO2 sonophotocatalysis led to complete cellulose degradation in 120 min with increasing the catalyst loading. TiO2 sonophotocatalysis was always faster than the respective individual processes due to the enhanced formation of reactive radicals as well as the possible ultrasound-induced increase of the active surface area of the catalyst. Their efficacy on enhancement of reactivity was discussed based on the kinetic parameters including, Michaelis constant Km, maximum reaction rate Vmax and initial reaction rate, correlating with ultrasonic conditions. Also, values of Km and Vmax were calculated in the absence and presence of ultrasonic and sonophoto waves.

RGO supported self-assembly of 2D nano sheet of (g-C3N4) into rod-like nano structure and its application in sonophotocatalytic degradation of an antibiotic

Graphitic carbon nitride (g-C3N4) is an analog of graphite due to its unique electronic structure. g-C3N4 based materials have been used in photocatalytic applications. However, pure g-C3N4 suffers from major shortcomings which include poor disparity, low surface area and a high recombination rate of photo generated electron-hole pairs that significantly reduce its photocatalytic activity. In this work, self-assembly of g-C3N4 sheet into rod shaped g-C3N4 was developed via a simple polymerisation method. A composite made of g-C3N4 nanorods and rGO (rGO-RCN) was also prepared. The band gap g-C3N4 was shifted from 2.77 to 2.6 eV evidented by UV-DRS data. As a result, rGO-RCN showed a relatively high absorption in the visible region. Moreover, a fast electron transfer rate was observed with rGO-RCN composite as conformed from PL analysis and photocurrent measurement. The formation of nanorod and sheet morphologies was confirmed via TEM analysis. The photocatalytic activities of prepared sheet-g-C3N4 (SCN), Rod g-C3N4 (RCN), reduced graphene oxide supported sheet-g-C3N4 (rGO-SCN) and reduced graphene oxide supported Rod-g-C3N4 (rGO-RCN) were evaluated using a commonly used antibiotic (tetracycline). Among these catalysts, rGO-RCN nanocomposite showed sonophotocatalytic activity 3 times higher compared to pure g-C3N4. This superior sonophotocatalytic activity could be due to enhanced visible light absorption of the material, active sites generated by ultrasound, and the high electron transport property of rGO.

Enhanced sonophotocatalytic degradation of bisphenol A using bimetal sulfide-intercalated MXenes, 2D/2D nanocomposite

A novel 2D Ti3C2Tx MXene (MX) co-catalyst and NixMg4-xS4 (NMS) nanocomposite (NMS@MX) was simply prepared through a hydrothermal method and utilized as a sonophotocatalyst for the degradation of bisphenol A (BPA). Because the remediation of wastewater containing endocrine-disrupting compounds is an important issue in environmental fields, BPA was selected as the main organic pollutant to clarify the sonophotocatalytic activity of NMS@MX in this study. We confirmed the successful synthesis of NMS@MX through Fourier-transform infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy analyses. The mineralization of BPA via sonophotocatalysis with NMS@MX was much faster and more efficient than by applying photolysis and sonolysis, separately. The NMS@MX sonophotocatalyst showed high sonophotocatalytic activity based on ~92% degradation of BPA within 60 min using both visible light and ultrasonication. This outcome could have resulted from the mitigation of the photo-corrosion of metal sulfides through heterojunction structures combined with the highly conductive MX co-catalyst. Furthermore, NMS@MX showed excellent sonophotostability over four consecutive cycles for the degradation of BPA with negligible loss of sonophotocatalytic activity. Finally, we proposed the sonophotocatalytic degradation pathway of BPA in the Sono/Vis/MNS@MX system (Sono = sonolysis; Vis = photolysis).

Sonophotocatalytic degradation of sulfadiazine by integration of microfibrillated carboxymethyl cellulose with Zn-Cu-Mg mixed metal hydroxide/g-C3N4 composite

This research aimed to prepare a recoverable sonophotocatalyst, in which microfibrillated carboxymethyl cellulose (MFC) acted as the Zn-Cu-Mg-mixed metal hydroxide/graphitic carbon nitride (MMH/g-C3N4) carrier. The characteristics of bare and composite sonophotocatalysts were analyzed by the XRD, FT-IR, BET, DRS, PL and FE-SEM equipped with the EDX mapping. The performance of prepared composites (MMH/g-C3N4@MFC) with various weight ratios of the MMH/g-C3N4 was studied for the sonophotocatalytic degradation of sulfadiazine (SDZ) as the model emerging contaminant. 93% of SDZ was degraded using the most effective catalyst (MMH/g-C3N4@MFC3) with 15% weight ratio of the MMH/g-C3N4 under the desired operating conditions including solution pH of 6.5, SDZ concentration of 0.15 mM and ultrasonic power of 300 W. The MMH addition to the g-C3N4 structure increased the separation of charge carriers generated via the visible light or ultrasound irradiations. Moreover, the MMH/g-C3N4 was dispersed uniformly on the MFC and consequently, more active sites were available to form reactive oxygen species (ROS), compared to powder form. Hydroxyl radicals (•OH) were determined as the main ROS in the SDZ degradation by performing a series of scavenging experiments. Less than 10% decrease in the degradation efficiency of SDZ was observed during five subsequent experiments, which indicated the proper retention of the MMH/g-C3N4 particles in the MFC. The adequate mineralization of SDZ (83% decrease in chemical oxygen demand (COD)) was obtained after 200 min of treatment. Eventually, ten degradation intermediates were identified by the GC-MS analysis and a plausible degradation mechanism for the contaminant was proposed.

Enhancement of Photocatalytic and Sonophotocatalytic Degradation of 4-nitrophenol by ZnO/Graphene Oxide and ZnO/Carbon Nanotube Nanocomposites

An approach involving ultrasonic irradiation/hydrothermal route was employed for fabricating a series of ZnO nanospheres-carbon nanotubes (Z/CNT) and reduced graphene oxides (Z/GO) nanocomposites, at different weight % ratios of both. The synthesized catalysts were tested in heterogeneous photocatalytic degradation of 4-nitrophenol (4-NP, 10 ppm) via Fenton approach in the attendance of visible light irradiation (160 W, λ > 420), ultrasonic illumination (60 W, 20 kHz) and during coupling the latter irradiations (sonophotocatalysis). The experimental parameters for the Photo-Fenton degradation of 4-NP at the surface of the Z(70)/CNT(30) catalyst were 40 mM H2O2, pH 4, catalyst dosage of 1.75 g/L and at 25 °C. The rate constants of 4-NP degradation using the sonophotocatalytic approach (0.3 min-1); that takes 15 min to accomplish, exceeded those of sonocatalytic (0.15 min-1) and photocatalytic (0.06 min-1) systems, unveiling the synergistic performance of the former system. These values were lower when performing the reaction at the same conditions but at pH 11 to elucidate the importance of the slow releasing of ∙OH in the acid range. The sono- and photo- coupled irradiations induced a synergy percentage comprised of 30 to demonstrate the efficacy of the adopted approach and the catalyst in the degradation of 4-NP.

Sonophotocatalytic degradation of sodium diclofenac using low power ultrasound and micro sized TiO2.

The nonsteroidal anti-inflammatory drug sodium diclofenac (DC) is an emerging water pollutant which resists conventional wastewater treatments. Here the sonophotocatalytic degradation of DC was carried out using micrometric TiO2 (both pristine and Ag-decorated), UV-A irradiation and 20kHz pulsed ultrasound. Sonophotocatalytic tests were compared with photolysis, sonolysis, sonophotolysis, sonocatalysis and photocatalysis data performed in the same conditions. A synergy index of over 2 was determined for tests with pristine TiO2, while values close to 1.3 were observed for Ag-TiO2. Reaction intermediates were studied by HPLC-MS, showing degradation mechanisms activated by hydroxyl radicals. Similar pathways were identified for photocatalytic and sonophotocatalytic tests, although the latter led to more oxidized compounds. Different reactor configurations (static and dynamic set ups) were studied. Sequential and simultaneous application of UV light and ultrasound led to similar performance. The role of water matrix was investigated using ultrapure and drinking water, showing marked detrimental effects of electrolytes on the DC degradation. Overall, the combined treatment proved more efficient than photocatalysis alone especially in demanding working conditions, like in drinking water matrices.

Sono-coprecipitation synthesis of ZnO/CuO nanophotocatalyst for removal of parathion from wastewater.

Semiconductor photocatalysis is an effective method used to degrade organophosphorus compounds. Here, the potential of a commonly mixed oxide semiconductor, ZnO/CuO, has been examined to degrade methyl parathion. Sono-coprecipitation method was used to provide ZnO/CuO nanocomposites, and it was applied to photocatalytic and sono-photocatalytic degradation of methyl parathion under solar light irradiation. Powder x-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), the Brunauer-Emmett-Teller (BET) surface area, field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM) were used to characterize the synthesized samples. The optimal experimental conditions such as ZnO/CuO photocatalyst 90:10M ratios, the initial concentration of 20mg/L parathion, 1g/L photocatalyst loading, no compressed air sparging, pH of 8, and ultrasonic power (60W and 80kHz) were used to degrade the parathion effectively. The parathion was fully (100% removal) degraded after 60min sono-photoirradiation in the optimal experimental conditions. A real water sample was used to examine the ability of the ZnO/CuO photocatalyst 90:10 to remove the parathion in the water-soluble ions. Graphical abstract.

Sono-photocatalytic degradation of tetracycline and pharmaceutical wastewater using WO3/CNT heterojunction nanocomposite under US and visible light irradiations: A novel hybrid system

In this paper, in-situ fabrication of tungsten oxide (WO3) on carbon nano-tube (CNT) was performed via sol-gel/hydrothermal method to prepare WO3/CNT nanocomposites and then coupled with visible light and ultrasound (US) irradiations for sono-photocatalytic removal of tetracycline (TTC) and pharmaceutical wastewater treatment. The as-prepared catalysts were characterized by FT-IR, XRD, TEM, UV-VIS DRS, FESEM, EDS, TGA, BET, BJH, EIS, and EDX techniques. The characterization tests, indicated successful incorporation of CTNs into the WO3 framework and efficient reduction of charge carries recombination rate after modifying with CNT. The investigation of experimental parameters verified that 60 mg/L TTC could be perfectly degraded at optimum operational parameters (WO3/CNT: 0.7 g/L, pH: 9.0, US power: 250 W/m2, and light intensity: 120 W/m2 over 60 min treatment. Trapping experiments results verified that HO radicals and h+ were the main oxidative species in degradation of TTC. The as-prepared photocatalysts could be reused after six successive cycles with an approximately 8.8 % reduction in removal efficiency. Investigation of the effect of real pharmaceutical wastewater revealed that this system is able to eliminate 83.7 and 90.6 % of TOC and COD, respectively after 220 min of reaction time. Some compounds with lower toxic impact and molecular weight, compared to raw pharmaceutical wastewater, were detected after treatment by sono-photocatalysis process. The biodegradability of real pharmaceutical wastewater was improved significantly after treatment by WO3/CNT sono-photocatalysis.

Removal of hazardous textile dyes from water using Ni impregnated ZnO through sonophotocatalytic degradation

Removal of hazardous textile dyes from water using Ni impregnated ZnO through sonophotocatalytic degradation

N, Cu co-doped TiO2@functionalized SWCNT photocatalyst coupled with ultrasound and visible-light: An effective sono-photocatalysis process for pharmaceutical wastewaters treatment

Abstract In this study, N-Cu co-doped TiO2 was decorated on the single-walled carbon nano-tube (marked as N-Cu co-doped TiO2@CNTs) via two-step sol–gel/hydrothermal synthesis method for the first time as a novel photocatalyst in coupling with ultrasound (US) waves. The catalyst properties were characterized via BET, Raman, FESEM, TEM, FTIR, XRD, EIS, PL, TGA, UV–Vis DRS, EDX and EDS dot mapping. These techniques confirmed the successful doping of both N and Cu elements on the CNTs impregnated with TiO2 nanoparticles. The investigation of effective operational parameters demonstrated that the total removal of sulfamethoxazole (SMXZ) could be achieved under pH of 6.0, catalyst dosage of 0.8 g/L, light intensity of 200 W, US power of 200 W, and initial SMXZ concentration of 60 mg/L within 60 min. SMXZ degradation kinetics over sono-photocatalytic process were in a good agreement with pseudo-first-order model. Quenching experiments illustrated that HO• and O2•– active species were more effective species for SMXZ degradation. The synthesized sono-photocatalyst could be recycled after six consecutive cycles of SMXZ degradation with an insignificant decrease in performance. A tentative mechanism and pathway for SMXZ were formulated. Pharmaceutical wastewater was treated through the optimum degradation conditions which showed that the sono-photocatalytic degradation eliminated 93% of COD and 89% of TOC within 180 min.

N/Ti3+ co-doping biphasic TiO2/Bi2WO6 heterojunctions: Hydrothermal fabrication and sonophotocatalytic degradation of organic pollutants

This study describes the one-step in situ hydrothermal construction of N/Ti3+ co-doping biphasic TiO2/Bi2WO6 heterojunctions (NT-TBWx) and investigates their sonophotocatalytic degradation of organic contaminants in water. The obtained samples are characterized in detail including X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Ultraviolet diffuse reflectance spectroscopy, etc. Their photocatalytic, sonocatalytic, and sonophotocatalytic performance are compared by the degradation of organic pollutants and found the degradation rate according to the order: photocatalysis < sonocatalysis < sonophotocatalysis. In addition, NT-TBWx samples present better sonophotocatalytic activity for the removal of methylene blue (MB), p-Nitrophenol, Rhodamine B, and levofloxacin compared with that of NT-TiO2 and pure TiO2. Especially, the highest sonophotocatalytic degradation rate is demonstrated for NT-TBW1. Additionally, the excellent stability of NT-TBWx samples is demonstrated by four cycles of sonophotocatalytic measurements with a tiny decline. Superoxide radical (·O2−) is found to dominate the sonophotocatalytic degradation process of MB. The synergic effect among the doping level, heterophase junction, and heterojunctions as well as between sonocatalysis and photocatalysis contribute to superior sonophotocatalytic activity. This work provides a new alternative architecture of TiO2-based nanomaterials and promotes their application in environmental issues.

The Sonophotocatalytic Degradation of Pharmaceuticals in Water by MnOx-TiO2 Systems with Tuned Band-Gaps

Advanced oxidation processes (AOPs) are technologies to degrade organic pollutants to carbon dioxide and water with an eco-friendly approach to form reactive hydroxyl radicals. Photocatalysis is an AOP whereby TiO2 is the most adopted photocatalyst. However, TiO2 features a wide (3.2 eV) and fast electron-hole recombination. When Mn is embedded in TiO2, it shifts the absorption wavelength towards the visible region of light, making it active for natural light applications. We present a systematic study of how the textural and optical properties of Mn-doped TiO2 vary with ultrasound applied during synthesis. We varied ultrasound power, pulse length, and power density (by changing the amount of solvent). Ultrasound produced mesoporous MnOx-TiO2 powders with a higher surface area (101–158 m2 g−1), pore volume (0-13–0.29 cc g−1), and smaller particle size (4–10 µm) than those obtained with a conventional sol-gel method (48–129 m2 g−1, 0.14–0.21 cc g−1, 181 µm, respectively). Surprisingly, the catalysts obtained with ultrasound had a content of brookite that was at least 28%, while the traditional sol-gel samples only had 7%. The samples synthesized with ultrasound had a wider distribution of the band-gaps, in the 1.6–1.91 eV range, while traditional ones ranged from 1.72 eV to 1.8 eV. We tested activity in the sonophotocatalytic degradation of two model pollutants (amoxicillin and acetaminophen). The catalysts synthesized with ultrasound were up to 50% more active than the traditional samples.

Kinetics of sonophotocatalytic degradation of an anionic dye nigrosine with doped and undoped zinc oxide

The current research focuses on the photocatalytic, sonocatalytic and sonophotocatalytic degradation of nigrosine dye with nitrogen-doped and undoped zinc oxide powders. The sonophotocatalytic degradation of dye was found to occur at a higher rate than during photo- or sonocatalytic processes. Nitrogen-doped and undoped zinc oxide powders were synthesized by a wet chemical method. Further, scanning electron microscopy (FESEM), electron dispersive X-ray (EDX), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), UV-VIS spectroscopy (UV-VIS) and transmission electron microscopy (TEM) were used for the characterization of N-doped ZnO. The kinetics of nigrosine degradation were also studied and the results indicated that the degradation kinetics of nigrosine followed the first-order kinetics. The rate constant and the percentage of degradation were found to be highest, 7.33 × 10-4 (s-1) and 92% respectively, for sonophotocatalytic process after 90 min of reaction. Due to an increase in the available surface area or active sites of the catalyst, a higher rate constant and degradation efficiency was observed in the sonophotocatalytic system than in the photocatalysis system.

Self-doping of Ti3+ in TiO2 through incomplete hydrolysis of titanium (IV) isopropoxide: An efficient visible light sonophotocatalyst for organic pollutants degradation

Herein, introduction of Ti3+ in TiO2 through incomplete hydrolysis of titanium tetra isopropoxide (TTIP) was demonstrated successfully for the first time. Interestingly, instantaneous addition of water to TTIP led to the formation of oxygen vacancies due to the incomplete hydrolysis and subsequent thermal activation induced the formation of Ti3+ site in the TiO2 as confirmed by EPR and XPS studies. Importantly, the slow addition of water to TTIP did not induce the formation of Ti3+ sites and indirectly ascertained the complete hydrolysis of TTIP. The catalytic efficiency of Ti3+-self-doped TiO2 was evaluated by sonophotocatalytic degradation of methyl orange (MO) dye and tetracycline (TC) antibiotics under visible light illumination. In comparison with individual effects of light and ultrasound, ∼4 and ∼1.2 folds synergistic effect was achieved for MO and TC degradation when ultrasound was combined with visible light due to synergistic production of OH radical by ultrasound and visible light.

Core/shell FeVO4@BiOCl heterojunction as a durable heterogeneous Fenton catalyst for the efficient sonophotocatalytic degradation of p-nitrophenol

In this study, a FeVO4@BiOCl p–n heterojunction with n-type porous FeVO4 nanorods as the core and p-type flower-like BiOCl nanostructures as the shell was successfully prepared by a facile hydrothermal method. The novel heterostructure was investigated as a durable heterogeneous Fenton catalyst for ultrasonic irradiation (US), ultraviolet irradiation (UV) and coupling irradiation systems (US/UV). Characterization of FeVO4@BiOCl core shell heterojunction was conducted by XRD, SEM, EDS elemental mapping, TEM, HRTEM, SAED, FTIR, Raman, BET, PZC, XPS and DRS. Several different experimental parameters, including irradiation time, H2O2 concentration, catalyst amount, initial concentration, and pH value, were optimized. The stability and reusability of the prepared FeVO4@BiOCl core shell heterojunction were evaluated as well. Mineralization experiments were carried out using the optimized parameters. The results showed that FeVO4@BiOCl core shell heterojunction exhibits a superior sonophotocatalytic performance compared to either sonocatalysis or photocatalysis. Moreover, the formation of p-n core@shell nanostructures could significantly increase the pHpzc, and to an excellent stability for the degradation of PNP after six cycles. The remarkable enhancement of the degradation performance of FeVO4@BiOCl core shell heterojunction can be attributed to the unique structure and morphology with a matched energy band structure owing to the internal electric field induced by the p–n junction, a high transfer efficiency and the efficient separation of e−/h+ pairs, resulting in a huge number of reactive species for the degradation of PNP. A plausible mechanism over FeVO4@BiOCl core shell heterojunction for the sonophotocatalytic degradation of PNP is proposed based on a special three-way, i.e. one as a photocatalyst and a two-way Fenton-like mechanism with the dissociation of H2O2. Active species trapping and calculated band gap energy were also discussed.

Fabrication of NiFe layered double hydroxide/reduced graphene oxide (NiFe-LDH/rGO) nanocomposite with enhanced sonophotocatalytic activity for the degradation of moxifloxacin

Herein a NiFe layered double hydroxide/reduced graphene oxide (NiFe-LDH/rGO) nanocomposite was synthesized in a hydrothermal method. The sonophotocatalytic implementation of NiFe-LDH/rGO nanocomposite was scrutinized for the degradation of moxifloxacin (MOX), as a model-emerging contaminant, from the solution. The structure of the synthesized samples was analyzed by XRD, FE-SEM, EDX, TEM, FTIR, BET, PL, and UV-Vis DRS analyses. To manifest the sonophotocatalytic performance of NiFe-LDH/rGO nanocomposite, the impact of the main operating parameters was examined for the degradation of MOX. The best sonophotocatalytic efficiency of 90.40% was achieved by using 1.0 g/L catalyst, 20 mg/L MOX, and an ultrasonic power of 150 W at a pH of 8 (natural) within 60 min. Moreover, the effects of the addition of various oxidants, dissolved gases, and various scavengers on the decomposition of MOX were investigated. A proposed mechanism was also presented for the decomposition of MOX in the presence of NiFe-LDH/rGO nanocomposite under the sonophotocatalytic system. By-products formed through sonophotocatalytic degradation process were recognized by the gas chromatography-mass spectrometry (GC-MS) technique. Finally, the reusability test of NiFe-LDH/rGO nanocomposite in the MOX degradation revealed that a drop of almost 13% occurred after five successive cycles.

Comment on “Sonophotocatalytic degradation of textile dyes over Cu impregnated ZnO catalyst in aqueous solution” by J. Shah et al., Process Saf. Environ. Prot. 2018. 116 (2018) 149–158

Comment on “Sonophotocatalytic degradation of textile dyes over Cu impregnated ZnO catalyst in aqueous solution” by J. Shah et al., Process Saf. Environ. Prot. 2018. 116 (2018) 149–158